Impact of Cover Crops on Soil Physical Properties Newell R. Kitchen Matt Volkmann Newell R. Kitchen Matt Volkmann October 21, 2009.

Impact of Cover Crops Impact of Cover Crops on Soil Physical on Soil Physical

PropertiesProperties

Impact of Cover Crops Impact of Cover Crops on Soil Physical on Soil Physical

PropertiesProperties

Newell R. KitchenNewell R. KitchenMatt VolkmannMatt Volkmann

Newell R. KitchenNewell R. KitchenMatt VolkmannMatt Volkmann

October 21, 2009October 21, 2009October 21, 2009October 21, 2009

Why do we do cover Why do we do cover crops?crops?

Cover: blanket, canopy, cloak, hood, layer, shield, overlay, veil, cap

On May 1, 1917 in Columbia, MO the first

erosion plot research in the US was initiated.

WHY Columbia?

Historical Loss of Soil from Historical Loss of Soil from ErosionErosion

• Average 5 inches of soil loss over the whole field • Extreme Loss > 16 inches of soil loss in localized areas• Over 150 years…. between 5 and 6 tons/year

Lost topsoil from erosionLost organic matterLost soil structureLower fertility

Lost topsoil from erosionLost organic matterLost soil structureLower fertility

What good is “cover” when you’ve lost 60-90% of the function of that original soil?

These degraded soils have lost so much of their original function……in many ways they are nearly dead and in need of life support!

What are the Hidden (i.e., below ground) Impacts Of Cover

Crops?

Summit Side Foot

Mulch tillage, Corn-soybean rotation (MTCS)

No-till, Corn-soybean-wheat rotation (NTCSW cover)

0.1

1

10

100

Summit Backslope Footslope

Ksa

t (m

m h

r-1)

b

a

a

a

How about Soil Hydraulic Conductivity?

NT CS

MT CS

NT CSWcover

How about Infiltration?

Do All Cover Crops Provide Equal Benefit?

Permanent grass managementPermanent grass management

2 Conservation Reserve 2 Conservation Reserve Program (CRP) systems: No Program (CRP) systems: No inputsinputs

Species: Tall fescue, orchard Species: Tall fescue, orchard grass, red clover or warm grass, red clover or warm season grassesseason grasses

Hay: Hay crop, N 90 kg/ha, Hay: Hay crop, N 90 kg/ha, Lime, P, and K by soil testLime, P, and K by soil test

Species: White clover, Species: White clover, orchard grass, Canadian orchard grass, Canadian wildrye, big bluestem.wildrye, big bluestem.

HAYCRP

CRP

HAY

CRP

CRP (cool)

CRP (warm)

hay (cool & warm)

0

10

20

30

40

50

60

70

Footslope Backslope Summit

Landscape

Ag

gre

ga

te s

tab

ility

, %

Min. Till CS (1)No Till CS (2)ICM No Till CSW (5)CRP (6)

How about Soil Aggregate Stability?

How about Soil Strength?

CS

b bb bb

ba

a

5

01

02

03

0

ACS1

ACS2

ACS3

CRP

Soi

l dep

th,

mHow about Total Soil Organic Carbon and Nitrogen?

2005 , 2007, 2009 Wheat Cover

2006 Cereal Rye/Red Clover

2007 Sudex (following wheat)

2008 Rye Grass

2009 Brassica Mix (following wheat)

What benefits are we noticing?What benefits are we noticing?

Results – Results – Temporal Differences in Temporal Differences in SQIsSQIs

Property and units 2003 2007

pH 6.18 6.34

P, mg/kg 7.6 15.1

K, mg/kg 60.9 133.6

SOC, g/kg 11.5 12.4

POM-C, g/kg 1.49 2.51

MnOxC, g/kg 0.344 0.342

Total N, g/kg 1.07 1.18

POM-N, g/kg 0.117 0.166

Highlighted items are significantly different between samplings

Results – Results – Temporal Differences in Temporal Differences in SQIsSQIs

-2 .0

-1 .0

0 .0

1 .0

2 .0

3 .0

4 .0

5 .0Tota l O rganic C arbon (g/kg)

0 .0 0 .5 1 .0 1 .5 2 .0 2 .5 3 .0 3 .5 4 .0 4 .5Particu la te O rganic M atter C arbon (g/kg)

-0 .010

-0 .008

-0 .006

-0 .004

-0 .002

0 .000

0 .002

0 .004Perm anganate-oxid izable C arbon (g/kg)

-0 .25

-0 .15

-0 .05

0 .05

0 .15

0 .25

0 .35

0 .45Tota l N itrogen (g/kg)

0 .02

0 .04

0 .06

0 .08

0 .10

0 .12

Particu la te O rganic M atter N itrogen (g/kg)

Avg. N O 3-N (kg ha -1 90cm -1) C over: 16.7 N o-C over: 118.8

0 20 40 60

NO 3-N (kg ha -1)

80

60

40

20

0

Pro

file

Dep

th (

cm)

Typical Positive Impacts

from Cover Crops on Soil Physical Properties

• Increased soil organic matterIncreased soil organic matter• Enhanced infiltrationEnhanced infiltration• Enhanced aerationEnhanced aeration• Improved soil Improved soil structure/aggregationstructure/aggregation• Decreased soil strength**Decreased soil strength**• Preventive of soil compactionPreventive of soil compaction• Reduced evaporation potentialReduced evaporation potential